1 files changed, 74 insertions, 0 deletions
diff --git a/ext/js/background/offscreen.js b/ext/js/background/offscreen.js
new file mode 100644
index 00000000..bc41d189
--- /dev/null
+++ b/ext/js/background/offscreen.js
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2023  Yomitan Authors
+ * Copyright (C) 2016-2022  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * ClipboardReader
+ */
+
+/**
+ * This class controls the core logic of the extension, including API calls
+ * and various forms of communication between browser tabs and external applications.
+ */
+class Offscreen {
+    /**
+     * Creates a new instance.
+     */
+    constructor() {
+        this._clipboardReader = new ClipboardReader({
+            // eslint-disable-next-line no-undef
+            document: (typeof document === 'object' && document !== null ? document : null),
+            pasteTargetSelector: '#clipboard-paste-target',
+            richContentPasteTargetSelector: '#clipboard-rich-content-paste-target'
+        });
+
+        this._messageHandlers = new Map([
+            ['clipboardGetTextOffscreen',                 {async: true,  contentScript: true,  handler: this._getTextHandler.bind(this)}],
+            ['clipboardGetImageOffscreen',                 {async: true,  contentScript: true,  handler: this._getImageHandler.bind(this)}]
+        ]);
+
+        const onMessage = this._onMessage.bind(this);
+        chrome.runtime.onMessage.addListener(onMessage);
+    }
+
+    _getTextHandler({useRichText}) {
+        return this._clipboardReader.getText(useRichText);
+    }
+
+    _getImageHandler() {
+        return this._clipboardReader.getImage();
+    }
+
+    _onMessage({action, params}, sender, callback) {
+        const messageHandler = this._messageHandlers.get(action);
+        if (typeof messageHandler === 'undefined') { return false; }
+        this._validatePrivilegedMessageSender(sender);
+
+        return invokeMessageHandler(messageHandler, params, callback, sender);
+    }
+
+    _validatePrivilegedMessageSender(sender) {
+        let {url} = sender;
+        if (typeof url === 'string' && yomichan.isExtensionUrl(url)) { return; }
+        const {tab} = url;
+        if (typeof tab === 'object' && tab !== null) {
+            ({url} = tab);
+            if (typeof url === 'string' && yomichan.isExtensionUrl(url)) { return; }
+        }
+        throw new Error('Invalid message sender');
+    }
+}